Method of making polyvinyl alcohol fibers



United States Patent M Japan No Drawing. Filed May 26, 1960, Ser. No.31,824 Claims priority, application Japan May 26, 1959 4 Claims. (Cl.8115.5)

This invention relates to the manufacture of polyvinyl alcoholicderivatives and to the formation of fibers from a spinning solutioncontaining said derivatives.

As described in US. patent application Ser. No. 856,334, filed December1, 1959, now US. Patent No. 3,007,228, the dyeability of polyvinylalcohol fibers can be markedly increased by spinning the fibers from amixture of an emulsified polymer formed from basic monomers and a watersolution of polyvinyl alcohol. When fibers spun from such a mixture aresubjected to benzalization, which has the effect of significantlyimproving the hot-water resistance and the elasticity of polyvinylalcohol, fibers can be obtained which have excellent elastic recoveryand dyeability without showing any significant drop in dye-absorption.This is substantially different from the results obtained by mixedspinning of watersoluble polymers containing basic nitrogen asheretofore practiced.

It is an object of this invention to provide a novel process forproducing fibers of polyvinyl alcohol having high hot water-resistance,high heat-resistance and desirable mechanical properties similar tothose of fibers produced solely from polyvinyl alcohol, yetcharacterized by a particularly high dyeability.

In accordance with this invention, spinning of fibers is elfected from aspinning fluid prepared by dispersing in a water solution of polyvinylalcohol an emulsion or fine powder of a water-insoluble polyvinylalcohol derivative obtained by etherification of polyvinyl alcohol withan epoxy compound containing basic nitrogen, ethyleneimine, or itsderivatives, combined with acetalization with an aldehyde containing nobasic nitrogen.

We have previously prepared emulsions or fine powders of awater-insoluble polyvinyl alcoholic derivative produced by acetalizationwith aldehydes containing basic nitrogen, and by acetalization withaldehydes containing no basic nitrogen, the second reaction beingcarried out simultaneously with prior to, or after the first reaction,depending upon the circumstances. The emulsions or fine powders obtainedin this way were dispersed in an aqueous solution of polyvinyl alcoholand mixed spinning was effected from this mixed solution. It was foundthat the fibers produced by spinning with this mixed solution could besubstantially improved in their dyeing characteristics with respect toacid and direct dyes not only when benzaldehyde was used for thetreatment to make the fibers insoluble after they were treated withheat, but when formaldehyde was employed for such treatment.

As the result of research subsequently performed, we have discoveredthat when emulsions or fine powders of a water-insoluble polyvinylalcohol derivative produced by aminoetherification using an epoxycompound or ethyleneimine, or its derivatives, as the compoundcontaining basic nitrogen, in combination with acetalization by means ofan aldehyde containing no basic nitrogen, which may be effected prior toor after aminoetherification. When the emulsions are dispersed in anaqueous solution of a polyvinyl alcohol to form a mixed spinningsolution, and when the fibers spun from this solution are 3,142,532Patented July 28, 1954 treated with heat and are subsequently subjectedto acetalization in accordance with conventional practice, theimprovement of the dyeing properties of the fibers is entirelysatisfactory and the same results are obtainable when the aldehyde usedfor acetalization is benzaldehyde.

It will be understood that the particle diameter of the fine powdersmade by the method of this invention should be within a range suitablefor mixed spinning. For this reason, emulsions or the fine powdershaving a diameter of less than 30 are suitably used. Fine powders havinga suitable diameter are readily prepared by the process of thisinvention. Furthermore, the quantity of basic nitrogen in thefinely-divided water-insoluble polyvinyl alcohol derivative should bemore than 0.2%, and it is advantageous to use the polymer containingbasic nitrogen in a proportion in relation to the polyvinyl alcohol suchthat the quantity of basic nitrogen is ODS-2.0% based on the polyvinylalcohol. The fibers spun from the spinning solution produced by themethod of this invention exhibit a substantial improvement in dyeingcharacteristics with respect to direct cotton dyes and with respect toacid woolen dyes, and yet any reduction of hot water-resistant,heat-resistant, or mechanical properties is negligible.

When eifecting the acetalization step to produce the emulsions or thefine powders suitable for the purposes of this invention,.it isgenerally desirable to do so under high speed agitation of the mixtureand it is preferable to add any of the various known surface activeagents or protective colloids to the solution. As surface active agents,various anionic, non-ionic, and cationic surface active agents aresuitably used, but inasmuch as an anionic surface active agent mayoccasionally tend to coagulate solid particles by forming a bond withbasic nitrogen, it is preferred to use a non-ionic surface active agentsuch as polyoxyethylenedodecyl ether, or a cationic surface active agentsuch as dodecyltrimethylammonium chloride. As protective colloids,compounds such as water-soluble starch, partially aminoacetalizedpolyvinyl alcohol, polyvinylpyrrolidone, and the like are suitably used.

To form a stable dispersion of the above-described solid polymerparticles in a water solution of polyvinyl alcohol, various proceduresmay be employed. Thus when the polyvinyl alcohol derivative is in theform of an emulsion, the emulsion may be directly mixed with a watersolution of polyvinyl alcohol, or it may be mixed with polyvinyl alcoholpowder and water may then be added to dissolve the powder.Alternatively, the emulsion may be heated, and polyvinyl alcohol powderor moist polyvinyl alcohol powder may be slowly added and dissolved inthe emulsion. When the polyvinyl alcohol derivative particles are in theform of a fine powder, the powder particles may be mixed with polyvinylalcohol powder and water added to dissolve the powder mixture or thepolyvinyl alcohol derivative particles may be mixed with a small amountof Water or a water solution of polyvinyl alcohol, and the paste of finepowder thus obtained may be mixed with polyvinyl alcohol. It will beunderstood, however, that various other procedures may be used.

It is possible to carry out spinning by means of the spinning fluidprepared by dispersing an emulsion or a fine powder of the polyvinylalcohol derivatives with polyvinyl alcohol by the method of thisinvention, with the addition of various types of water-soluble polymerssuch as soluble starch, polyvinylpyrrolidone, aminoacetalized polyvinylalcohol, various kinds of pigments such as titanium oxide, and acids,alkalis, and salts such as sodium sulfate, and the like. Accordingly, itis possible to simul taneously effect improvements in the transparencyand in the form of the cross-section of the fibers, particularly whenthe fibers are formed by wet spinning.

The fiber spun by the method of this invention may be subjected tothermal elongation, i.e. hot-stretching, heat-treatment andinsolubilization treatments in the same manner as fibers formed solelyfrom ordinary polyvinyl alcohol. For effecting insolubilizationtreatments there may be employed acetalization by means of aldehydessuch as formaldehyde, acetaldehyde, chloracetaldehyde, butylaldehyde,nonylaldehyde, benzaldehyde, monochlorbenzaldehyde, l-naphthaldehyde,glyoxal, malonaldehyde, glutaraldehyde, terephthalaldehyde, and thelike. The fibers may also be subjected to treatments with inorganicreagents such as titanation, and chromination. Various other knowninsolubilization treatments may also be employed.

Compounds containing the basic nitrogen suitable for use in accordancewith the method of this invention include epoxy compounds containingbasic nitrogen which may be formed by the reaction of epichlorohydrinwith any alkyl or cycloalkyl secondary amine such as dimethylamine,diethylamine, dibutylamine, didodecylamine, dihexylamine,chlorohexylamine, methyl-butylamine, and methyl-ethylamine, and thelike, ethyleneimine, any of the derivatives of ethyleneimine containingthe ethyleneimine ring such as those formed by the reaction ofethyleneimine with melamine, and the like, all of which form an etherlinkage by reaction with the hydroxyl group of the polyvinyl alcohol.

Aldehydes suitably used in the method of this invention, are any of thealiphatic or aromatic or aralkyl aldehydes such as formaldehyde,acetalaldehyde, propionaldehyde, butylaldehyde, 2-ethyl-hexylaldehyde,nonylaldehyde, naphthalaldehyde, salicylaldehyde, benzaldehyde,trimethyl-tetrahydro benzaldehyde, and cinnamaldehyde, and like alkyl,aromatic and aralkyl aldehydes or their acetals.

The invention will be further understood from the following specificexamples of practical application. However, it will be understood thatthese examples are not to be construed as limiting the scope of thepresent invention in any manner. In these examples, all parts are byweight, unless otherwise indicated.

Example 1 An aqueous solution containing 4% polyvinyl alcohol having anaverage degree of polymerization of 1000, 2% formaldehyde and 50%sulphuric acid was allowed to react at a temperature of 50 C. for aperiod of 60 minutes with agitation at the rate of more than 1000 r.p.m.To this solution was then gradually added a 1% aqueous solution of adispersing agent in an amount equal to the volume of the initialquantity. There was thus produced, in finely-divided form, a polyvinylalcohol derivative having a 65% degree of acetalization and a particlediameter of 2-3 r. The finely-divided particles were collected byfiltration and washed with water thoroughly to remove any free acid andaldehyde.

Three grams of these formalized polyvinyl alcohol particles were mixedwith 1.2 g. of l-diethylamine-2,3-epoxy propane. The mixture wassubjected to the reaction at a temperature of 130 C. for a period of 3hours in a pressure-proof container. After the reaction was completed,the resultant product was washed with hot water (60 C.) three times. Theparticle diameters of the powder obtained were 1-3/1. and the producthad a basic nitrogen content of 1.5%.

The fine powder was then mixed with polyvinyl alcohol in the amount of10% of the powder based on the polyvinyl alcohol. The mixture wasdissolved by the addition of water to form a spinning solution inaccordance with the usual procedure in forming polyvinyl alcoholspinning solutions. The resultant solution was subjected to wet spinningin a coagulation bath of Glaubers salt. The spun fibers were drawn by400% at a temperature of 235 C. for a period of 5 seconds. The fiberswere then treated with heat at constant length at a temperature of 235C. for a period of seconds. Some of the fibers treated in this way weresubjected to formalization in an aqueous solution containing 5%formaldehyde, 15% sulphuric acid, and 15 Glaubers salt at a temperatureof 70 C. for a period of 2 hours. The remaining fibers were subjected tobenzalization in an aqueous solution containing 2% benzaldehyde, 15%sulphuric acid, and 40% methanol at a temperature of 60 C. for a periodof 2 hours. The fibers (1) treated with formaldehyde were 41.5%acetalized and the fibers (2) treated with benzaldehyde were 31.0%acetalized.

All of the thus-treated fibers were dyed in a dye bath (ratio of bath1:100) containing 3% acid scarlet, 4% an acid dye and 3% sulphuric acid(all percentages based on the weight of the fibers) at a temperature ofC. for a period of 60 minutes. Both fibers (l) and (2) satisfactorilyabsorbed the dye, and no loss in their dyeing properties was observedwhen the fibers were dyed after heat treatment. Moreover, the presenceof dyed fine powders was found when the dyed fibers were observed bymeans of an optical miscroscope.

Example 2 Ten grams of polyvinyl alcohol and 5 g. of ethyleneimine weremixed, and the mixture was allowed to react in a pressure-proofcontainer at a temperature of C. for a period of 4 hours. The derivativeof the polyvinyl alcohol formed by this reaction was washed withmethanol 3 times. This derivative, which was an aminoetherifiedpolyvinyl alcohol had a basic nitrogen content of 1.0%.

An aqueous solution containing 4% of this aminoetherified polyvinylalcohol, 2% formaldehyde and 50% sulphuric acid was subsequently reactedat a temperature of 50 C. for a period of 1 hour. To the resultantsolution there was then added an equal volume of an aqueous solutioncontaining 1% of a surface active agent. The surface active agentsolution was gradually added drop wise while the polyvinyl alcoholsolution was agitated at the rate of more than 1000 r.p.m. at atemperature of 40 C. By this process, fine water-insoluble particleshaving a 70% degree of acetalization and containing basic nitrogen wereobtained. These particles were filtered and washed and the washedparticles were formed into an aqueous emulsion.

The fine water-insoluble emulsified particles were then mixed with apolyvinyl alcohol in the proportion of 8% based on the polyvinyl alcoholand a spinning solution with a concentration of 35% was prepared. Thespinning solution was extruded into air in accordance with theconventional dry-spinning process.

The resultant fibers were drawn at a temperature of 220 C. with adrawing ratio of 500% and they were then shrunk or relaxed at atemperature of 225 C. by 20%. The fibers were acetalized by theprocedure described in Example 1 and the fibers were then dyed with anacid dye. Both the formalized and the benzalized fibers exhibitedexcellent dyeing properties, and yet no adverse effect on the physicalproperties of the benzalized fibers was observed, as shown in thefollowing table wherein these fibers are compared with conventionalpolyvinyl alcohol fibers containing no basic nitrogen.

Furthermore, when the fibers made by the process of this invention weretreated at a temperature of 235 C. for a period of 30 minutes, nocoloring of the fibers was observed and the degree of their whitenesswas more than 95.

Example 3 When an aqueous solution containing 3% polyvinyl alcoholhaving an average degree of polymerization of 1300, 2% formaldehyde, and20% sulphuric acid was reacted at a temperature of 50 C. for a period of120 minutes under agitation of more than 1000 r.p.m., fine particles offormalized polyvinyl alcohol were formed. The diameters of theseparticles were of the order of 5p, and the degree of acetalization was70%. The particles were filtered and washed, and they were then driedfor a period of 20 hours in air.

Ten grams of these fine particles of the polymer obtained were mixedwith 5 g. of ethyleneimine and the resultant mixture was reacted in apressure-proof container at a temperature of 110 C. for a period of 3hours. The quantity of basic nitrogen in the fine particles after thisreaction was 1.4%.

These fine particles were mixed with a 1% aqueous solution of asurface-active agent to form a emulsion. The emulsion was spun and theresultant fibers were heattreated and acetalized as described inExample 1. The resultant fibers were then dyed with Acid Scarlet 31R,and the dyeing properties of the fibers after acetalization were foundto be good.

The surface-active or dispersing agents or dispersants and protectivecolloids which are suitably employed are, in addition to those mentionedabove, any of the many dispersing agents and protective colloids knownto those skilled in the art of making emulsions or dispersions ofpolymers. In the foregoing examples, for instance,polyoxyethylenedodecyl ether is suitably used as the dispersant orsurface-active agent.

It will therefore be understood that, unless otherwise indicated,conventional operations and conventional apparatus are employed incarrying out the process of this invention including conventional mixingand emulsifying units. Similarly, conventional dyeing techniques andapparatus are suitably employed upon the fibers produced by the processof this invention. The conditions and the relative relationships setforth in the examples are those preferred in carrying out the process ofthe invention but it Will be understood that other conditions andrelationships may be used within the scope of the invention.

The spinning fluids produced in accordance with the present inventionare particularly suitable for the spinning of fibers in accordance withknown processes used in the spinning of polyvinyl alcohol and polyvinylalcohol derivatives, particularly the so-called wet-spinningtechniquesas described, for example, in Cline et al. US. Patent2,610,360 and Osugi et al. Patent No. 2,906,594. An especially preferredspinning technique is described in copending application Serial No.336,166 of Tomonari et al., filed February 10, 1953, now U.S. Patent No.2,988,802.

After formation of the fibers by wet spinning the filaments can befurther treated by stretching, heat treating, acetalization, and thelike to produce fibers with desirable and outstanding properties, usingknown techniques as described in said patents.-

It will also be understood that various changes and modifications inaddition to those indicated above may be made in the embodiments hereindescribed Without departing from the scope of the invention as definedin the appended claims. It is intended, therefore, that all mattercontained in the foregoing description shall be interpreted asillustrative only and not as limitative of the invention.

We claim:

1. A process of producing fibers of polyvinyl alcohol of improvedproperties which comprises adding to an aqueous solution of polyvinylalcohol, water-insoluble derivatives of polyvinyl alcohol infinely-divided form, mixing and distributing said derivatives in saidsolution and spinning said fibers from the resultant spinning solution,said derivatives containing more than 0.2% basic nitrogen and being theproducts resulting from reaction of polyvinyl alcohol with an aldehydecontaining no basic nitrogen and with a member of the group consistingof ethylene-imine, the reaction product of ethylene-imine and melamine,and the reaction product of epichlorhydrin and an alkyl secondary amine,and acetalizing said fibers.

2. A polyvinyl alcohol spinning solution efiective to provide fibers ofpolyvinyl alcohol of improved prop erties formed by adding to an aqueoussolution of polyvinyl alcohol, water-insoluble derivatives of polyvinylalcohol in finely-divided form, and mixing and distributing saidderivatives in said solution, said derivatives containing more than 0.2%basic nitrogen and being the products resulting from reaction ofpolyvinyl alcohol with an aldehyde containing no basic nitrogen and witha member of the group consisting of ethylene imine, the reaction productof ethylene-imine and melamine, and the reaction product ofepichlorhydrin and an alkyl secondary amine.

3. A process of producing fibers of polyvinyl alcohol of improvedproperties which comprises adding to an aqueous solution of polyvinylalcohol, water-insoluble derivatives of polyvinyl alcohol in finelydivided form, mixing and distributing said derivatives in said solution,and spinning said fibers from the resultant spinning solution, saidderivatives containing more than 0 .2% basic nitrogen and being theproducts resulting from reaction of polyvinyl alcohol with an aldehydecontaining no basic nitrogen and with the reaction product ofepichlorhydrin and an alkyl secondary amine and acetalizing said fibers.

4. A process of producing fibers of polyvinyl alcohol of improvedproperties which comprises adding to an aqueous solution of polyvinylalcohol, water-insoluble derivatives of polyvinyl alcohol in finelydivided form, mixing and distributing said derivatives in said solution,and spinning said fibers from the resultant spinning solution, saidderivatives containing more than 0 .2% basic nitrogen and being theproducts resulting from reaction of polyvinyl alcohol with an aldehydecontaining no basic nitrogen and with ethylene imine, and acetalizingsaid fibers.

References Cited in the file of this patent UNITED STATES PATENTS2,296,225 Ulrich Sept. 15, 1942 2,341,413 Pense et al. Feb. 8, 19442,906,594 Osugi et al. Sept. 29, 1959

1. A PROCESS OF PRODUCING FIBERS OF POLYVINYL ALCOHOL OF IMPROVEDPROPERTIES WHICH COMPRISES ADDING TO AN AQUEOUS SOLUTION OF POLYVINYLALCOHOL, WATER-INSOLUBLE DERIVATIVES OF POLYVINYL ALCOHOL INFINELY-DIVIDED FORM, MIXING AND DISTRIBUTING SAID DERIVATIVES IN SAIDSOLUTION AND SPINNING SAID FIBERS FROM THE RESULTANT SPINNING SOLUTION,SAID DERIVATIVES CONTAINING MORE THAN 0.2% BASIC NITROGEN AND BEING THEPRODUCTS RESULTING FROM REACTION OF POLYVINYL ALCOHOL WITH AN ALDEHYDECONTAINING NO BASIC NITROGEN AND WITH A MEMBER OF THE GROUP CONSISTINGOF ETHYLENE-IMINE, THE REACTION PRODUCT OF ETHYLENE-IMINE AND MELAMINE,AND THE REACTION PRODUCT OF EPICHLORHYDRIN AND AN ALKYL SECONDARY AMINE,AND ACETALIZING SAID FIBERS.